Due to rapid progress in the semiconductor industry and electronic technologies, technologies for manufacturing infrared measuring sensors have also progressed significantly. Infrared measuring sensors not only apply to the medical purpose of measuring body temperature but also apply to scientific, commercial and military purposes, such as laser detection, missile guidance, infrared spectrometry, remote control, burglarproofing equipment and thermal image detection. Conventionally, infrared measuring sensors include thermal type infrared measuring sensors and photon type infrared measuring sensors. Since the thermal type infrared measuring sensor is utilized more conveniently, it is widely used in various applications.
Generally, the thermal type infrared imaging sensor is operated at about room temperature, and due to the poor heat conductance of air, the heat transmitted from a target heat source to the senor is significantly dissipated, so that an infrared imaging chip thereof has to be tightly packaged in vacuum for increasing sensitivity. For maintaining the normal operation of the infrared imaging sensor, a thermoelectric cooler is often used in the package as a temperature stabilizer.
Since infrared radiation can be absorbed by most materials in the world, a conventional lens material of the infrared thermal imaging system is limited to some materials having lower infrared absorptivity. Accordingly, the conventional infrared lens of the infrared thermal imaging system is very expensive, decreasing the marketability of the infrared thermal imaging system.
In addition, the image of the infrared thermal imaging system is formed by measuring infrared energy radiating from the object. Therefore, the image quality thereof is not as clear and distinguishable as an image taken by a visible light video camera. However, in a dark environment, for example outdoors at night, the infrared thermal imaging system can provide a better image than the visible light video camera.